Allow pixelflinger to work when NX (No Execute) is enabled.
Instead of allocating memory from the (non executable) heap,
allocate memory using mspace and ensure that we use mprotect
to mark it as PROT_EXEC. This allows pixelflinger to
continue to work even when NX protections are enabled.
Testing: Using the ApiDemos market app, verify that
Apidemos -> Graphics -> OpenGL ES -> GLSurfaceView
works when "adb shell setprop debug.egl.hw 0" is set.
Change-Id: Ib569cd2543c6fa25688ee76325a712bc2347450b
diff --git a/libpixelflinger/codeflinger/CodeCache.cpp b/libpixelflinger/codeflinger/CodeCache.cpp
index 29410c8..5877ff4 100644
--- a/libpixelflinger/codeflinger/CodeCache.cpp
+++ b/libpixelflinger/codeflinger/CodeCache.cpp
@@ -19,6 +19,8 @@
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
#include <cutils/log.h>
#include <cutils/atomic.h>
@@ -39,15 +41,14 @@
Assembly::Assembly(size_t size)
: mCount(1), mSize(0)
{
- mBase = (uint32_t*)malloc(size);
- if (mBase) {
- mSize = size;
- }
+ mBase = (uint32_t*)mspace_malloc(getMspace(), size);
+ mSize = size;
+ ensureMbaseExecutable();
}
Assembly::~Assembly()
{
- free(mBase);
+ mspace_free(getMspace(), mBase);
}
void Assembly::incStrong(const void*) const
@@ -75,11 +76,32 @@
ssize_t Assembly::resize(size_t newSize)
{
- mBase = (uint32_t*)realloc(mBase, newSize);
+ mBase = (uint32_t*)mspace_realloc(getMspace(), mBase, newSize);
mSize = newSize;
+ ensureMbaseExecutable();
return size();
}
+mspace Assembly::getMspace()
+{
+ static mspace msp = create_contiguous_mspace(2 * 1024, 1024 * 1024, /*locked=*/ false);
+ return msp;
+}
+
+void Assembly::ensureMbaseExecutable()
+{
+ long pagesize = sysconf(_SC_PAGESIZE);
+ long pagemask = ~(pagesize - 1); // assumes pagesize is a power of 2
+
+ uint32_t* pageStart = (uint32_t*) (((uintptr_t) mBase) & pagemask);
+ size_t adjustedLength = mBase - pageStart + mSize;
+
+ if (mBase && mprotect(pageStart, adjustedLength, PROT_READ | PROT_WRITE | PROT_EXEC) != 0) {
+ mspace_free(getMspace(), mBase);
+ mBase = NULL;
+ }
+}
+
// ----------------------------------------------------------------------------
CodeCache::CodeCache(size_t size)